The advantages of using differential circuits in radio frequency (RF) integrated circuits (ICs) and devices having those ICs are readily recognized by designers and are highly desired in the field. In these products, since input and/or output signals are often desired to be single ended, typically a differential to single ended converter (D/SE) converter is used in designs and product offerings.
A challenge in design is to ensure a current source biasing a differential pair does not have high impedance at high frequencies. As a result, a balanced/unbalanced impedance (“BALUN”), often a high frequency transformer, is used for differential/single ended (D/SE) conversions.
Unfortunately, a BALUN, though operatively and functionally a desirable option, is moderately expensive and requires a sizeable footprint set aside such that its additional bulk and physical presence on the printed circuit board, or board side, often limits optimal design and usage needs in view of current design efforts. Additionally, at least two energy transferences are conventionally undertaken to convert the differential RF IN signal to a single ended RF OUT signal, of which each conversion results in energy losses due to inefficiencies existing and inherent in the balancing, transferences and conversions.
Further, attempts to overcome the losses by alternative BALUN locations have proven ineffective and equally or more inefficient or expensive.